TH may be valuable in assessing the overall training state of ER. TH concentrations change too slowly to be a frequent marker of monitoring OTS, but are related to markers of decreased performance. Monitoring dietary intake, and fatigue may be predictive markers to assess OTS and training status of female ER.
To determine absolute and relative (adjusted for body mass) strength, mean power, and mean velocity for upper and lower body resistance exercises, forty-seven young boys and girls participated in maximal strength testing. Healthy young boys and girls, ages 3- to 7-years old, were tested for one-repetition maximum (1-RM) strength, and 70% of 1-RM to determine mean power and mean velocity on the chest press and leg press exercises. Adult weight machines were modified to accommodate the smaller size and lower strength levels of the children. A 2 × 4 (sex × age) ANOVA was used to determine age and sex differences in performance. No interaction or sex differences were observed for any variable at any age. 1-RM strength, mean power, and mean velocity significantly increased across ages (p ≤ .05). When adjusted for body mass, the changes were insignificant, with one exception. Relative mean power for the bench press increased with age. Data indicated children from 3-7 years of age are capable of performing strength and power tests, but may require more attempts at maximal loads compared with adults. It appears that muscular strength and velocity during this stage of development are primarily dependent on increasing body mass, whereas power is influenced by additional variable(s).
Extracellular signal-regulated protein kinase 1/2 (ERK1/2) moderates skeletal muscle growth; however, chronic responses of this protein to unique resistance exercise (RE) paradigms are yet to be explored. The purpose of this investigation was to describe the long-term response of ERK1/2 following circuit weight training (CWT), recreationally weight training (WT), powerlifting (PL) and weightlifting (WL). Independent t-tests were used to determine differences in trained groups compared to sedentary controls. Total ERK1/2 content was lower in PL and WL compared to their controls (p ≤ 0.05). Specific trained groups displayed large (WL: pERK/total-ERK; d = 1.25) and moderate (CWT: total ERK1/2; d = 0.54) effect sizes for altered kinase expression compared to controls. The results indicate ERK1/2 expression is down-regulated after chronic RE in well-trained weightlifters and powerlifters. Lower expression of this protein may be a method in which anabolism is tightly regulated after many years of high-intensity RE.
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